Amines are organic derivatives of ammonia, NH3IntroductionClassification of Amines Primary amines Secondary amines Tertiary aminesChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.1

Classify the following amines:123213Aliphatic aminesAromatic aminesChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.1

IUPAC NomenclatureIn primary amines, the suffix amine replaces the e in the name of the parent alkane3 2 1Secondary and tertiary amines are named as N-substituted derivatives of primary amines2 12Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.2propaneamineeN-methylethaneeamine

Examples:Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.2

StructureIUPAC NameMethanamine2-propanamineCyclopentanamineN-methylpentanamineN-ethyl-N-methyl ethanamine

When multiple functional groups are present and the NH2 group does not take priority, it is named as an amino substituentExamples:IUPAC Nomenclature2 11234Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.2ethanoic acid2-aminophenol2,4-diamino

IUPAC NomenclatureAromatic amines are named as derivatives of anilineChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.2N-ethyl-N-methylaniline

Most primary amines are named as alkylaminesCommon NameChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.2

StructureIUPAC Namemethylamineethylaminepropylaminedimethylaminemethylethylamine

(i) Boiling PointBoth primary and secondary amines can form intermolecular hydrogen bonds.Tertiary amines cannot form hydrogen bonds to each other.1 amines2 amines3 amines19.3Boiling pointSolubility BasicityChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature

The table below compares the boiling points of isomeric amines.Examples:Boiling Point : CH3CH2CH2NH2 > CH3CH2NH(CH3) > (CH3)3N

AminesClassRelative molecular massBoliling points/oCCH3CH2CH2NH215949CH3CH2-NH-CH325937 CH3 | CH3-N-CH33594

(i) Boiling PointAmines have higher boiling points than alkanes or haloalkanes of similar relative molecular mass due to

Amines have lower boiling points than alcohols or carboxylic acids of comparable molecular weight because intermolecular hydrogen bonding (Nitrogen is less electronegative than the Oxygen)H- bond in RNH2 is weaker than the H- bond in ROH and RCOOHChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.3Boiling pointSolubility Basicity

The table below compares the boiling points of organic compounds of comparable relative molecular mass.Examples:5864.559-0.512.548.6AlkaneHaloalkaneAmine

AminesTypeRelative molecular massBoliling points/oCCH3CH2CH2CH3butaneCH3CH2ClchloroethaneCH3CH2CH2NH2 1-propanamine

(i) Boiling PointAmines have higher boiling points than alkanes or haloalkanes of similar relative molecular mass due to

Amines have lower boiling points than alcohols or carboxylic acids of comparable molecular weight because intermolecular hydrogen bonding (Nitrogen is less electronegative than the Oxygen)H- bond in RNH2 is weaker than the H- bond in ROH and RCOOHChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.3Boiling pointSolubility Basicity

The table below compares the boiling points of organic compounds of comparable relative molecular mass.Examples:Boiling Point : Carboxylic acid > Alcohol > Amine > Haloalkane > Alkane5864.5596060-0.512.548.697.2118AlkaneHaloalkaneAmineAlcoholCarboxylic acidCH3CH2CH2OH1-propanolCH3COOHethanoic acidCH3CH2CH2NH2 1-propanamine

AminesTypeRelative molecular massBoiling points/oCCH3CH2CH2CH3butaneCH3CH2ClchloroethaneCH3CH2CH2NH2 1-propanamine

(ii) SolubilityAll amines including tertiary amines, are capable of forming hydrogen bonds with water molecules. Thus simple amines (amines of fewer than 5 carbons) are generally water soluble and dissolve to form basic aqueous solutionsChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.3Boiling pointSolubility Basicity

Comparison the solubility between 1,2 and 3amine3 hydrogen bonds per a 1 amine molecule2 hydrogen bonds per a 2 amine molecule1 hydrogen bond per a 3 amine moleculeThe solubility :3 < 2 < 1 Increasing solubility

BasicityAn amine is a nucleophile (a Lewis base) because its lone pair of non-bonding electrons on nitrogenAmmonium ion Ammonia Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.3Boiling pointSolubility Basicity

An alkyl group is electron donating group, and it stabilises the alkylammonium ion by dispersing its positive chargeBasicity (i) Inductive effectalkylammonium ion 1 Amine Stabilised by the alkyl groupChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.3Boiling pointSolubility Basicity

alkylammonium ion 1 Amine alkylammonium ion 2 Amine Strength as a base : Methyl, 1, 2 IncreasingChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.3Boiling pointSolubility Basicity

Basicity (ii) Resonance effectAromatic amines (e.g., aniline) are weaker bases than the corresponding aliphatic and cyclic aminesExample: Cyclohexylamine Aniline pKb = 3.36 pKb = 9.42Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.3Boiling pointSolubility Basicity

Aromatic amines are less basicBasicity (ii) Resonance effectThe lone pair electrons of nitrogen atom are delocalised and overlapped with the aromatic ring electrons system make it less available for bonding to H+arylamines are stabilised due to the 4 resonance structures Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.3Boiling pointSolubility Basicity

19.4Reduction of nitro compoundReduction of nitrilesReduction of nitro compoundsAromatic amines can be prepared by reduction of nitro compounds using Zn/H+ or SnCl2/H+Zn/H+ orSnCl2/H+nitrobenzeneanlineReduction of amidesHoffmanns degradation of amidesChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : NomenclatureAniline

Reduction of nitrilesNitriles are reduced to primary amines by H2 / catalyst, LiAlH4 / H+ or NaBH4 / H+.

Example : Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.4Reduction of nitro compoundReduction of nitrilesReduction of amidesHoffmanns degradation of amides

Reduction of amidesReduction of an amide using LiAlH4 / H+ or NaBH4 / H+ can yield a primary, secondary, or tertiary amine depending on the type of amide usedChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.4Reduction of nitro compoundReduction of nitrilesReduction of amidesHoffmanns degradation of amides

Example : Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.4Reduction of nitro compoundReduction of nitrilesReduction of amidesHoffmanns degradation of amides

Hoffmanns degradation of amidesOn warming a primary amide with bromine in solution of NaOH, a primary amine is formed.This reaction is used to synthesise primary alkyl and aryl amines.The elimination of carbonyl group is shortening the length of carbon chain by one carbon atom.Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.4Reduction of nitro compoundReduction of nitrilesReduction of amidesHoffmanns degradation of amides

Example : Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.4Reduction of nitro compoundReduction of nitrilesReduction of amidesHoffmanns degradation of amides

19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterReaction with acyl chlorides1 and 2 amines are acylated to form N-substituted amides3 amines are not acylated because they do not have a H atom attached to N atom.Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : NomenclatureFormation of dye

Reaction with acid anhydride1 and 2 amines are acylated to form N-substituted amides3 amines are not acylated because they do not have a H atom attached to N atom.Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Reaction with benzenesulphonyl chlorideHinsbergs testThis reaction is used to differentiate between 1, 2 and 3 amines.Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Benzenesulphonyl chloride reacts with a 1 amine to form a white precipitate (N-substituted sulphonamides)1 aminesAcidic hydrogenN-substituted sulphonamides have an acidic hydrogen, N-H.Therefore, it dissolve in aqueous NaOH.Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

N,N-disubstituted sulphonamides do not have an acidic hydrogen, N-H.2 aminesTherefore, it dissolve in aqueous NaOH.Benzenesulphonyl chloride reacts with a 2 amines to form a white precipitate (N,N-disubstituted sulphonamide)Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

3 amines3 amine do not gives visible reaction with benzenesulphonyl chlorideSummary of Hinsbergs test:Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Reaction with nitrous acid (NaNO2 + HCl)Nitrous acid (HNO2) is a weak and unstable acid.It is always prepared in situ, by treating cold sodium nitrite (NaNO2) with an aqueous solution of a cold dilute hydrochloride acid (-5C).Nitrous acid reacts with all classes of aminesNitrous acid test can be used to distinguish: 1 aliphatic and 1 aromatic amines 1 and 2 aliphatic aminesChapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Primary aliphatic amines react with nitrous acid to yield highly unstable aliphatic diazonium salts1 amines (Aliphatic)Observation :Formation of gas bubbles (N2) Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Primary arylamines react with nitrous acid to give arenediazonium salts1 amines (Aromatic)Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature1 aliphatic amines and 2 aliphatic amines 19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Primary aliphatic aminesForm a mixture of alkenes, alcohols, alkyl halides and nitrogen gas. Secondary aliphatic aminesForm secondary N-nitrosamines as yellow oil, which is stable under the reaction conditions.

Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : NomenclatureReaction with bromine waterAniline reacts with aqueous bromine to yield white precipitatesNH2 group is an activating and ortho-para directors group(2,4,6-tribromoaniline)Observation: White precipitate formed19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : NomenclatureFormation of dye Primary arylamines react with nitrous acid to give arenediazonium salts which are stable at 0 C Arenediazonium salts also undergo coupling reaction with aromatic compounds with strong electron donating group, such as OH and NR2 at the para position to yield azo compounds Azo compounds are usually intensely coloured and relatively inexpensive compounds, they are used as dyes 19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye

Chapter 19 : Amines19.3 : Physical Properties 19.4 : Preparation19.5 : Chemical properties19.1 : Introduction19.2 : Nomenclature19.5Reaction with :Acyl chlorideAcid anhydrideBenzenesulphonyl chlorideNitrous acidBromine waterFormation of dye